Auto merge of #44272 - Dushistov:master, r=alexcrichton
Auto merge of #44272 - Dushistov:master, r=alexcrichton

add test for not optimized `pow` with constant power

Closes #34947

GBGamer/rust,aidancully/rust,GBGamer/rust,aidancully/rust,aidancully/rust,graydon/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,graydon/rust,GBGamer/rust